The incidents are said to have taken place at YMCA Swanscombe Children's Centre Pre School and have resulted in a full-scale investigation involving police, the nursery and social services.
No criminal charges have been brought, but the boy's mother is now considering civil action.
The mother of the child allegedly assaulted is considering civil action
The parent, who does not wish to be named, said her son was undergoing counselling after allegedly being slapped in the face and dragged in two separate incidents.
She said: "My son's behaviour changed. He was coming home upset, he was having terrible nightmares and wetting the bed.
"I kept asking the nursery if anything was wrong and they told me there was no problem, but when I would drop him off he would grab hold of my leg. He was petrified.
"My son's behaviour changed. He was coming home upset, he was having terrible nightmares and wetting the bed..." - mum of boy allegedly assaulted
"The police have been absolutely fantastic but say they won’t prosecute because of his age.
"It wasn't until last week that a social worker actually turned up. It's been 10 weeks and this is the first bit of support I've been given. I think the way it’s been handled has been disgusting.
"We haven't even had a letter from the nursery explaining what they're doing. I haven't got a clue."
A nursery spokesman said: "A member of staff has been suspended from duty following a complaint. We take any complaint very seriously.
"It is subject to a full investigation and until that is completed, I cannot make any further comments at this stage."
The matters have also been reported to Ofsted.